1. Field of the Invention
This invention relates generally to electrical switching apparatus and, more particularly, to trip actuator assemblies for circuit breakers.
2. Background Information
Electrical switching apparatus include, for example, circuit switching devices, circuit interrupters, such as circuit breakers, network protectors, contactors, motor starters, motor controllers, and other load controllers. Electrical switching apparatus such as circuit interrupters and, in particular, circuit breakers of the molded case variety, are well known in the art. See, for example, U.S. Pat. No. 5,341,191. Circuit breakers are used to protect electrical circuitry from damage due to an over-current condition, such as an overload condition or a relatively high level short circuit or fault condition. Molded case circuit breakers typically include a pair of separable contacts per phase. The separable contacts may be operated either manually by way of a handle disposed on the outside of the case or automatically in response to an over-current condition.
In an exemplary embodiment, circuit breakers include an operating mechanism, which is designed to rapidly open and close the separable contacts, a trip unit assembly, which senses over-current conditions, and a trip actuator assembly. The trip actuator is actuated by the trip unit assembly in response to an overcurrent condition and moves the operating mechanism to a trip state. In the trip state the separable contacts move to their open position.
Trip unit assemblies have often included mechanical devices that react magnetically or thermally to over-current conditions. Presently, electric circuits are also used to detect an over-current condition. As electric circuits do not react magnetically or thermally to over-current conditions, the electric circuit must be coupled to an electronic trip mechanism. For example, an electronic trip mechanism may be, without limitation, a flux shunt trip actuator. An electronic trip mechanism, such as, but not limited to, a flux shunt trip actuator needs a reset device. It is known to provide a separate reset actuator for a flux shunt trip actuator. That is, the reset actuator is separate from other elements such as, but not limited to, the circuit breaker handle.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in trip actuator assemblies therefor.